How did Oklahoma's foundation code change for homes in 2022?

Reviewed by Preston, Oklahoma foundation repair consultant · Updated 2026-10-14

In short: Oklahoma builds houses under the International Residential Code (IRC) with state amendments. The 2018 IRC rule, effective September 14, 2022, added rebar to all footings, set anchor bolt spacing, and barred trenching into the soil zone that supports a footing. A home's construction date tells you which of these rules applied when it was built.

Why does a home's construction date matter?

The rules in force when a house was built shape what is under it: how its footings were reinforced, how the frame was bolted down, and whether later trenching near the foundation was restricted. Older homes predate these amendments. For how building practice changed decade by decade, see construction era by decade.

What are Oklahoma's 2018 IRC foundation amendments?

The Oklahoma Uniform Building Code Commission adopted the 2018 IRC by permanent rule effective September 14, 2022 ¹. Its Chapter 4 (Foundations) amendments include:

A cold joint is where concrete poured at different times meets, such as a footing poured first and a stem wall poured later. No. 4 rebar is half-inch reinforcing steel.

Trenching near footings (R403.1.9)

The added section protects the soil that carries a footing's load. Trenching parallel to footings and walls may not extend into the bearing plane, whose upper boundary runs downward at 45 degrees from the outside bottom edge of the footing ¹. The rule expressly covers trenching for plumbing, electrical, storm shelters and pools ¹. This connects to settlement problems described in erosion, undermining and washout voids.

Frost depth is local

The state rule leaves the frost depth line in the climate table blank for the local authority having jurisdiction to fill in, and notes that deeper footings than the code figure may be required ¹. City values are discussed in permits, licensing and frost depth and freeze-thaw and frost depth.

Storm shelters

The same rule requires storm shelters to follow the ICC 500 standard with added requirements, and sets a minimum design wind speed of 250 miles per hour for shelters statewide ¹. In-ground garage shelters must have a rim at least 1 inch above the garage floor ¹.

When did Oklahoma homes move from crawl spaces to slabs?

Slab-on-grade houses were still uncommon in Tulsa in the mid-1950s ⁵. A University of Oklahoma survey of Tulsa's Lortondale neighborhood, where 211 homes were built mainly from 1954 to 1956, describes its slab-on-grade foundations as "unusual for Tulsa residential construction at the time" ⁵. In those houses the heating and cooling ductwork was laid into the slab, first as sheet metal and later as cardboard pipe to save money ⁵. Ducts cast into a slab can be affected when the slab cracks or moves; see slab on grade.

Older Tulsa neighborhoods predate that shift. The representative listed homes in the Maple Ridge Historic District date from 1913 to 1927, with walls of brick, hollow tile, stucco and stone ⁸. For homes of that age, see pier and beam crawl space.

Today slabs dominate. In 2024, 97.9% of new single-family homes in the West South Central census division (Oklahoma, Texas, Arkansas and Louisiana) were built on slabs, compared with 73% nationally ⁶.

Have any Oklahoma cities set stricter local rules?

After the May 20, 2013 tornado, Moore became the first U.S. city to adopt building rules aimed specifically at limiting tornado damage ⁷. New homes there must be built to resist winds up to 135 mph, compared with the 90 mph nationally accepted standard cited at the time ⁷. The city council approved 11 recommendations drawn from engineers' review of the 2013 damage ⁷.

What rules apply to manufactured homes?

Manufactured homes follow a separate set of rules. New homes in Oklahoma must be installed to HUD's federal installation standards (24 CFR Part 3285) or the manufacturer's approved instructions by a state-licensed installer ². Used homes follow Oklahoma's generic support standard, which assumes soil bearing of at least 1,500 psf and allows block piers spaced up to 6 feet on center ³. See manufactured homes data.

What soils does the code have to deal with?

Code footings sit on Oklahoma soils that can be highly expansive. A 1978 Oklahoma Agricultural Experiment Station study described Kirkland soil, sampled in Canadian County, as very plastic and highly expansive, which restricts its use for most engineering purposes ⁴. It also found Bethany, Kirkland and Norge soils have enough montmorillonite to make them unstable for many engineering uses ⁴. See shrink-swell and active zone and slab on grade.

Related

• Construction era by decade
• Codes and permits
• Original construction deficiency
• Slab on grade
• Pier and beam crawl space
• Additions and mixed foundations